The present invention relates generally to the field of latching systems and, in its most preferred embodiments, to the field of key operated, T-handle latching systems for use in vending machines.
A latching system secures a link between two or more bodies. It is well known that the strength and precision of this connection, as well as the speed and ease with which it can be both established and disengaged, are factors which affect the usefulness of a latching system. By way of example, but not limitation, one environment which requires a latching assembly to perform well with respect to each of these factors is that of vending machines. A vending machine door and the frame to which it is attached are two bodies which require a link that is strong and precise, as well as one which can be both created and disengaged both quickly and easily. Many vending machines contain money boxes and currency validators which attract hordes of vandals attempting to illegally access the machines; therefore, vending machines require latching systems which provide very strong links. Also, many vending machines are actually large refrigerated containers and, therefore, require a good seal which results from a precise connection. Furthermore, vending machines require frequent attention by service operators who replenish the supply of vendable items and collect money. The speed and ease with which the latching system may be operated are factors which affect the operator's productivity and efficiency.
One well-known type of latching system frequently used in the vending machine field is the common T-handle system. This type of latching system typically includes a T-handle housing connected to the vending machine door, a T-handle nested therein, a key-operated cylinder lock contained within the T-handle, a post member connected to the T-handle, and a receiving assembly connected to the vending machine frame for receiving the post member, thereby a link. In unlatching a typical T-handle assembly, rotation of a key causes a lock bolt of the cylinder lock to retract, allowing a spring to extend a nested T-handle from within a T-handle housing. Upon extension, the T-handle may be rotated by the operator to release the post member from the receiving assembly, thus allowing the door to be opened. A few typical T-handle systems are disclosed in the following U.S. Pat. Nos.: 3,089,329, 3,089,330, 3,111,833, 3,122,012, 3,213,654, 3,222,899, 3,234,765, 3,285,043, 3,299,678, 3,302,434, 3,550,412, 4,552,001.
The post member and receiving assembly incorporated by many of the common T-handle systems include a post member with a threaded distal end and a receiving assembly which includes a correspondingly threaded nut. Although many of these screw & nut systems provide strong and precise links, the amount of time and degree of effort required to create and disengage the links through repetitively rotating the T-handle are drawbacks to many of these systems. This problem was at least partially addressed in U.S. Pat. No. 4,974,888, which disclosed a faster-acting receiving assembly which reduced the amount of time required to create a link. However, because the post member still required "unscrewing", the amount of time required to disengage the link was not significantly reduced by the device therein disclosed.
Other common T-handle systems, such as that disclosed in U.S. Pat. No. 3,234,765, utilize a cam-type (quarter-turn) post member along with a locking cam and an inclined locking shoulder connected to the door frame. This type of latching system only requires the T-handle to be rotated through a fraction of a turn to alternately create or disengage a link. Although quick-releasing, one drawback of this type of latching system is that the vending machine door must first be placed in contact with the vending machine frame before the T-handle can be rotated to create a secured link. In other words, unlike the quick-receiving latching system discussed above with reference to U.S. Pat. No. 4,974,888, the linking process disclosed in U.S. Pat. No. 3,234,765 does not include the option of first pushing the T-handle into the T-handle housing so that the lock bolt extends to secure the nesting and then simply closing the door, thereby transferring the axial force used to close the door into force which directly accelerates the linking process. Furthermore, many cam-type latching systems provide less security than other types of latching systems.
In an attempt to provide latching systems which overcome these and other problems, the inventor of the present invention has previously invented several quick-acting latching systems, some embodiments of which utilize a T-handle assembly (and others which do not), including U.S. patent Ser. No. 07/358,888, filed May 30, 1989, allowed Apr. 23, 1990, now U.S. Pat. No. 5,027,630, and U.S. patent Ser. No. 07/403,665, filed Sep. 6, 1989, allowed Oct. 16, 1990 and now U.S. Pat. No. 5,022,243. These latching systems are what shall be referred to herein as fractional-rotation latching systems which are quick-acting with respect to both creating and dissolving a link and are also systems which transfer door closure force directly into force which accelerates the linking process and strengthens the resulting link. Because of the abundance of T-handle systems currently being used in vending machines throughout the world, especially those utilizing the screw & nut method, there is a need to be able to retrofit those systems with quick-acting systems, thus utilizing the various existing T-handles and T-handle housings. In furtherance of this objective, several problems exist in adapting the various typical T-handle systems.
Because of the prevalence of the T-handle systems which utilize the screw & nut method, operators frequently assume that a particular T-handle is to be continuously rotated to unscrew the post member. Because the present inventor's previously patented latching systems do not employ the typical screw & nut method, continuous rotation of a T-handle in those inventions is a waste of time. There is, therefore, a need in the industry to provide a means of identifying to an operator whether a particular T-handle assembly requires continuous rotation or whether mere fractional rotation will suffice.
One of the objects of the present invention is to provide a retrofit-capable, latching system which mechanically identifies the latching system to an operator as a fractional-rotation latching system by limiting the amount of allowable relative rotation between the T-handle and T-handle housing. With respect to the previously discussed cam-type (quarter-turn) latching system, as disclosed in U.S. Pat. No. 3,234,765, a cam washer is used in conjunction with a stop pin extending exteriorly from the T-handle housing to limit the amount of allowable rotation. However, many currently existing T-handle housings which utilize the screw & nut method, thus having no clearly inherent reason to limit rotation, do not include an externally extending stop pin. Therefore, the rotation-limiting device disclosed in that patent could not be used with many of the existing T-handle housings which do not include an externally extending stop pin.
Another aspect of many of the T-handle systems which employ the screw & nut method relates to the lost motion feature. During closure, after the seal has become sufficiently tight through rotation of the T-handle, the T-handle may not be in alignment with the T-handle housing. Further turning of the T-handle in the tightening direction, in order to align the T-handle with the T-handle housing, often requires an inordinate amount of rotation force, but rotation of the T-handle in the un-tightening direction to align the T-handle and T-handle housing often unacceptably reduces the pressure on the seal. Many of the common T-handle systems solve that problem through providing a lost motion connection between the T-handle and the post member, as disclosed in U.S. Pat. No. 3,122,012. This feature allows for a limited degree of reverse rotation after tightening so that the T-handle may be aligned with and then pushed into the T-handle housing This reverse rotation is disassociated from the post member so that the post member remains in a tight configuration, hence the lost motion.
This lost motion function is frequently accomplished through interaction between a pair of clutch lugs attached to the rear bearing wall of the T-handle and a clutch pin attached to the post member. The clutch pin is allowed to rotate freely between the clutch lugs so that a certain amount of "slop" is provided for the lost motion function. The rear passageway in the T-handle is also regularly circular, thus providing no restriction against this relative rotation between the T-handle and the post member. By contrast, in fractional-rotation latching systems, the presence of "slop" is detrimental to the latching system's reliable operation. There exists, therefore, a need for a device which will remove this "slop" and provide for a more continuous rotational connection between a post member and a variety of the existing T-handles.
U.S. Pat. No. 4,552,001, discussed above, discloses a T-handle which does not contain the common clutch lugs, but provides a square-shaped passageway which interacts with a cam-type post member which has a segment with an axially extending square cross-sectional profile. Although the T-handle and post member are in continuous rotational connection, many common T-handles include a regularly circular rear passageway rather than this irregularly-shaped rear passageway. There is a need, therefore, to provide a retrofit-capable device for eliminating "slop" in many of the currently existing T-handle assemblies.